The present invention relates to a wafer processing apparatus, a wafer processing method, and an SOI wafer fabrication method and, more particularly, to a wafer processing apparatus, a wafer processing method, and an SOI wafer fabrication method which process a wafer by dipping the wafer into a processing solution.
Wet etching is a typical example of processing performed by dipping a wafer into a solution. One subject of wet etching is to improve the in-plane uniformity. Conventionally, the in-plane uniformity is ensured by supplying fresh etching solution to the reaction surface by circulating the etching solution in a bath.
Another example of the processing performed by dipping a wafer into a solution is wafer cleaning processing. Japanese Patent Laid-Open No. 8-293478 has disclosed a wafer cleaning apparatus which increases the wafer cleaning efficiency by applying ultrasonic waves while vertically moving and rotating wafers contained in a carrier cassette in a solution by a cam mechanism.
Another example of the wafer cleaning apparatus is a cassetteless wafer cleaning apparatus. A cassetteless wafer cleaning apparatus is generally an apparatus in which rod members are arranged parallel to each other, grooves are formed in these rod members, and wafers are cleaned while being supported by these grooves. In an apparatus which cleans wafers contained in a carrier cassette, portions of the wafers in the grooves of the carrier cassette are difficult to clean. Also, since most portions of the two sides of each wafer are covered with constituent members of the carrier cassette, the cleaning solution for wafers is mostly supplied from an opening in the lower portion of the carrier cassette. This tends to result in poor cleaning. A cassetteless wafer cleaning apparatus is very effective to solve these problems. Japanese Patent Laid-Open No. 7-169731 has disclosed a cassetteless wafer cleaning apparatus capable of processing wafers of different sizes.
The wafer cleaning apparatus described in Japanese Patent Laid-Open No. 8-293478 cannot uniformly clean wafers because the strength of ultrasonic waves is made uneven by the constituent members of the carrier cassette. In this wafer cleaning apparatus, the carrier cassette is essential to prevent a fall of wafers when the wafers are rotated or vertically moved by the cam mechanism. The carrier cassette is commonly made from a resin such as PFA or PEEK, but these materials do not easily transmit ultrasonic waves. This decreases the efficiency of the cleaning processing.
Also, the wafer cleaning apparatus described in Japanese Patent Laid-Open No. 7-169731 is very effective to improve poor cleaning. However, the apparatus cannot uniformly clean wafers because the wafers are cleaned while being fixed in a bath. Additionally, since contact portions between wafer support members and wafers are fixed during cleaning, these contact portions are difficult to clean.
The present invention has been made in consideration of the above situation and has as its object to make wafer processing uniform.
A wafer processing apparatus according to the present invention is a wafer processing apparatus for processing a wafer by dipping the wafer into a processing solution, comprising a wafer processing bath, and a rotary support mechanism for supporting a wafer while rotating the wafer by a plurality of rod members arranged substantially parallel to each other.
The wafer processing apparatus preferably further comprises ultrasonic generating means for generating ultrasonic waves in the processing bath.
In the wafer processing apparatus, the rotary support mechanism preferably applies a rotating force to a wafer by rotating at least a rod member, which supports the wafer from a bottom surface side of the processing bath, of the rod members.
In the wafer processing apparatus, the rotary support member preferably applies a rotating force to a wafer by rotating the rod members in the same direction.
In the wafer processing apparatus, each rod member preferably has a groove for limiting movement of a wafer in an axial direction.
In the wafer processing apparatus, the rotary support mechanism preferably comprises driving force generating means for generating a driving force for rotating a wafer outside the processing bath.
In the wafer processing apparatus, the rotary support mechanism preferably further comprises a crank mechanism for transmitting the driving force generated by the driving force generating means to the rod members.
The wafer processing apparatus preferably further comprises a driving mechanism for rocking the rotary support mechanism in the processing bath.
The wafer processing apparatus preferably further comprises a driving mechanism for floating or dipping the rotary support mechanism.
In the wafer processing apparatus, the processing bath preferably comprises a circulating mechanism including an overflow bath.
In the wafer processing apparatus, the circulating mechanism preferably comprises means for reducing contamination of a wafer caused by particles which may be produced by the rotary support mechanism.
In the wafer processing apparatus, the ultrasonic generating means comprises an ultrasonic bath, an ultrasonic source, and an adjusting mechanism for adjusting a position of the ultrasonic source in the ultrasonic bath, and ultrasonic waves are transmitted to the processing bath via an ultrasonic transmitting medium placed in the ultrasonic bath.
In the wafer processing apparatus, at least portions of the processing bath and the rotary support mechanism, which may come into contact with a processing solution, are preferably made of a material selected from the group consisting of quartz and plastic.
In the wafer processing apparatus, at least portions of the processing bath and the rotary support mechanism, which may come into contact with a processing solution, are preferably made of a material selected from the group consisting of a fluorine resin, vinyl chloride, polyethylene, polypropylene, polybutyleneterephthalate (PBT), and polyetheretherketone (PEEK).
In the wafer processing apparatus, the rotary support mechanism preferably supports a wafer by four rod members.
In the wafer processing apparatus, the rod members are preferably arranged in a position where rotation of a wafer having an orientation flat is not prevented by the orientation flat when the wafer is processed.
A wafer processing apparatus according to the present invention is a wafer processing apparatus for processing a wafer by dipping the wafer into a processing solution, comprising a wafer processing bath, support means for supporting a wafer from both sides and below by a rod member to hold the wafer substantially perpendicular to a bottom surface of the processing bath, and driving means for rotating the supported wafer.
The wafer processing apparatus preferably further comprises ultrasonic generating means for generating ultrasonic waves in the processing bath.
In the wafer processing apparatus, the driving means preferably applies a rotating force to a wafer by rotating the rod member.
In the wafer processing apparatus, the rod member preferably has a groove for limiting movement of a wafer in an axial direction.
A wafer processing method according to the present invention is a wafer processing method of processing a wafer by dipping the wafer into a processing solution, wherein a wafer is rotated while being supported from two sides and below by a rod member, the wafer being held substantially perpendicular to a bottom surface of a processing bath.
In the wafer processing method, it is preferable that while a wafer is rotated in the processing bath, ultrasonic waves be generated in the processing solution.
The wafer processing method is suited to wafer etching by using an etching solution as the processing solution.
The wafer processing method is suited to etching of a wafer having a porous silicon layer by using an etching solution as the processing solution.
An SOI wafer fabrication method according to the present invention is an SOI wafer fabrication method of fabricating an SOI wafer by using the wafer processing method described above in a part of fabrication steps.
A wafer processing method according to the present invention processes a wafer by using the wafer processing apparatus described above.
A wafer processing method according to the present invention etches a specific layer formed on a wafer by using the wafer processing apparatus described above.
An SOI wafer fabrication method according to the present invention fabricates an SOI wafer by using the wafer processing method described above in a part of fabrication steps.
Further objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments of the present invention with reference to the accompanying drawings.